cerebrovascular and trauma Flashcards
what is cerebral oedema
Excess accumulation of fluid in the brain parenchyma
2 types of cerebral oedema
vasogenic
* disruption of BBB with trauma
* -> free movement of fluid
* -> oedema (endothelial lining with tight junctions, very regulated transfer of fluid across this)
cytotoxic
* secondary to cellular injury e.g. hypoxia/ ischemia
* -> kill cells that release fluid into the parenchyma
* -> hypoxic and ischemic damage
Result is raised intracranial pressure
macroscopic brain and CT of cerebral oedema
Sulci are pushed together
Cant see into the gyri
Oedematous brain
Lost all definition of sulci and gyri
summarise the path of CSF
Lateral ventricle have chorid plexus – make CSF – pass into 3rd – down cerebral aqueduct – into 4th – some down central canal in spinal cord but most bathes brain in subarachnoid space
Ultimately resorbed into superior saggital sinus through arachnoid granulation
what is non-communicating hydrocephalus
obstruction of flow of CSF
mostly in cerebral aqueduct
in neonates - choroid plexus blocks the flow
Rx
* Can bypass – catheter into ventricle – drain into the abdomen
* Can knock out floor of 3rd ventricle to allow CSF straight into subarachnoid space
what is communicating hydrocephalus
no obstruction but problems with reabsorption of CSF into venous sinuses
normal ICP
7-15mmHg for supine adult
Consequences of raised ICP
can be due to space occupying lesions, oedema or both
because of: Unyielding bony wall of skull and inflexible dural folds, raised ICP->
Herniation of brain structures
types of brain herniation
Subfalcine – brain tissue pushed under falcine cerebri
Can herniate medial temporal lobe into the posterior fossa - uncle herniation/transtentorial herniation
Tonsillar herniation – contents of posterior fossa into foramen magnum – fatal
definition of a stroke
clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal, and at times global loss of cerebral function, with symptoms lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin
note: This definition includes stroke due to cerebral infarction, primary intracerebral haemorrhage, intraventricular haemorrhage and most cases of subarachnoid haemorrhage
It excludes subdural haemorrhage, epidural haemorrhage, intracerebral haemorrhage (ICH) or infarction caused by infection or tumour
what is a TIA
warning stroke
caused by a clot
<5mins
no permanent injury to brain
1/3 of those with TIA get significant infarct within 5 years - need to determine what the cause of risk is
summarise Non-traumatic intra-parenchymal haemorrhage
haemorrhage into parenchyma
due to rupture of small intraparenchymal vessel
most common in basal ganglia
hypertension responsible in >50%
Can get small bleeds in basal ganglia – called lacuna infaracts or bleed – may not have an avert clinical effect – may not be sx – because compensated for elsewhere
sx of Non-traumatic intra-parenchymal haemorrhage
severe headache,
vomiting,
rapid loss of consciousness,
focal neurological signs
summarise ateriovenous malformation
can occur anywhere in CNS
Blood straight from arterial to venous
Don’t supply the local tissues very well
Can rupture
sx between 2nd adn 5th decade
high pressure -> massive bleeding - surgical emergency
seen on angiography
high morbidity and mortality
sx of arteriovenous malformation
haemorrhage,
seizures,
headache,
focal neurological deficits
AVM
AVM
Massive vessels – not much brain tissue
cavernous angioma
what is a subarachnoid haemorrhage and the cause
rupure of berry aneurysm - weakness of vessel wall
80 % - internal carotid artery bifurcation, 20% occur within the vertebro-basilar circulation
30% of pts have multiple aneurysms
Greatest risk of rupture when 6-10mm diameter
SAH
SAH - Blood around the brainstem and the base of the brain
treatment of cerebral aneurysms
endovascular treatment - coils
Aneurysms found because have a scan for something else
Neuroradiologists through femeral – fill aneurysm with coil
Risk of rupture during surgery is low
what are the vascular territories
MCA – lateral and subcortical
Anterior – all the way to posterior junction
Posterior – occipital and inferior temporal
which artery is blocked
middle cerebral
differentiate between infarct and haemorrhage
what are contusions
Brain in collision with skull
Surface “bruising”
If pia mater torn, then becomes laceration
Lateral surfaces of hemispheres, inferior surfaces of frontal and temporal lobes
Coup or contrecoup
summarise diffuse axonal injury
Occurs at moment of injury
Shear & tensile forces affecting axons
Commonest cause of coma (when no bleed)
Midline structures particularly affected e.g. corpus callosum, rostral brainstem and septum pellucidum
